On the dashboard I see grayed out spinners.
Disk I/O not being displayed under Virtual Machine. The spinner is gray and does not spin.
Problem with vCenter. If vCenter does not display metrics, this is the cause of the problem
VM | Performance Tab | Advanced | Select Disk in Swith to dropdown box | Chart Options | Look for counters Read rate, Read requests, Write rate, Write Request
If these counters do not exist then please contact VMware to address the issue
If the counters are missing in vSphere client then Foglight is not going to have those metrics either resulting in gray spinners (no data).